xref: /openbmc/linux/net/netfilter/xt_IDLETIMER.c (revision 54451f60) 
1 /*
2  * linux/net/netfilter/xt_IDLETIMER.c
3  *
4  * Netfilter module to trigger a timer when packet matches.
5  * After timer expires a kevent will be sent.
6  *
7  * Copyright (C) 2004, 2010 Nokia Corporation
8  * Written by Timo Teras <ext-timo.teras@nokia.com>
9  *
10  * Converted to x_tables and reworked for upstream inclusion
11  * by Luciano Coelho <luciano.coelho@nokia.com>
12  *
13  * Contact: Luciano Coelho <luciano.coelho@nokia.com>
14  *
15  * This program is free software; you can redistribute it and/or
16  * modify it under the terms of the GNU General Public License
17  * version 2 as published by the Free Software Foundation.
18  *
19  * This program is distributed in the hope that it will be useful, but
20  * WITHOUT ANY WARRANTY; without even the implied warranty of
21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
22  * General Public License for more details.
23  *
24  * You should have received a copy of the GNU General Public License
25  * along with this program; if not, write to the Free Software
26  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
27  * 02110-1301 USA
28  */
29 
30 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
31 
32 #include <linux/module.h>
33 #include <linux/timer.h>
34 #include <linux/list.h>
35 #include <linux/mutex.h>
36 #include <linux/netfilter.h>
37 #include <linux/netfilter/x_tables.h>
38 #include <linux/netfilter/xt_IDLETIMER.h>
39 #include <linux/kdev_t.h>
40 #include <linux/kobject.h>
41 #include <linux/workqueue.h>
42 #include <linux/sysfs.h>
43 
44 struct idletimer_tg_attr {
45 	struct attribute attr;
46 	ssize_t	(*show)(struct kobject *kobj,
47 			struct attribute *attr, char *buf);
48 };
49 
50 struct idletimer_tg {
51 	struct list_head entry;
52 	struct timer_list timer;
53 	struct work_struct work;
54 
55 	struct kobject *kobj;
56 	struct idletimer_tg_attr attr;
57 
58 	unsigned int refcnt;
59 };
60 
61 static LIST_HEAD(idletimer_tg_list);
62 static DEFINE_MUTEX(list_mutex);
63 
64 static struct kobject *idletimer_tg_kobj;
65 
66 static
67 struct idletimer_tg *__idletimer_tg_find_by_label(const char *label)
68 {
69 	struct idletimer_tg *entry;
70 
71 	list_for_each_entry(entry, &idletimer_tg_list, entry) {
72 		if (!strcmp(label, entry->attr.attr.name))
73 			return entry;
74 	}
75 
76 	return NULL;
77 }
78 
79 static ssize_t idletimer_tg_show(struct kobject *kobj, struct attribute *attr,
80 				 char *buf)
81 {
82 	struct idletimer_tg *timer;
83 	unsigned long expires = 0;
84 
85 	mutex_lock(&list_mutex);
86 
87 	timer =	__idletimer_tg_find_by_label(attr->name);
88 	if (timer)
89 		expires = timer->timer.expires;
90 
91 	mutex_unlock(&list_mutex);
92 
93 	if (time_after(expires, jiffies))
94 		return sprintf(buf, "%u\n",
95 			       jiffies_to_msecs(expires - jiffies) / 1000);
96 
97 	return sprintf(buf, "0\n");
98 }
99 
100 static void idletimer_tg_work(struct work_struct *work)
101 {
102 	struct idletimer_tg *timer = container_of(work, struct idletimer_tg,
103 						  work);
104 
105 	sysfs_notify(idletimer_tg_kobj, NULL, timer->attr.attr.name);
106 }
107 
108 static void idletimer_tg_expired(struct timer_list *t)
109 {
110 	struct idletimer_tg *timer = from_timer(timer, t, timer);
111 
112 	pr_debug("timer %s expired\n", timer->attr.attr.name);
113 
114 	schedule_work(&timer->work);
115 }
116 
117 static int idletimer_check_sysfs_name(const char *name, unsigned int size)
118 {
119 	int ret;
120 
121 	ret = xt_check_proc_name(name, size);
122 	if (ret < 0)
123 		return ret;
124 
125 	if (!strcmp(name, "power") ||
126 	    !strcmp(name, "subsystem") ||
127 	    !strcmp(name, "uevent"))
128 		return -EINVAL;
129 
130 	return 0;
131 }
132 
133 static int idletimer_tg_create(struct idletimer_tg_info *info)
134 {
135 	int ret;
136 
137 	info->timer = kmalloc(sizeof(*info->timer), GFP_KERNEL);
138 	if (!info->timer) {
139 		ret = -ENOMEM;
140 		goto out;
141 	}
142 
143 	ret = idletimer_check_sysfs_name(info->label, sizeof(info->label));
144 	if (ret < 0)
145 		goto out_free_timer;
146 
147 	sysfs_attr_init(&info->timer->attr.attr);
148 	info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL);
149 	if (!info->timer->attr.attr.name) {
150 		ret = -ENOMEM;
151 		goto out_free_timer;
152 	}
153 	info->timer->attr.attr.mode = 0444;
154 	info->timer->attr.show = idletimer_tg_show;
155 
156 	ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr);
157 	if (ret < 0) {
158 		pr_debug("couldn't add file to sysfs");
159 		goto out_free_attr;
160 	}
161 
162 	list_add(&info->timer->entry, &idletimer_tg_list);
163 
164 	timer_setup(&info->timer->timer, idletimer_tg_expired, 0);
165 	info->timer->refcnt = 1;
166 
167 	INIT_WORK(&info->timer->work, idletimer_tg_work);
168 
169 	mod_timer(&info->timer->timer,
170 		  msecs_to_jiffies(info->timeout * 1000) + jiffies);
171 
172 	return 0;
173 
174 out_free_attr:
175 	kfree(info->timer->attr.attr.name);
176 out_free_timer:
177 	kfree(info->timer);
178 out:
179 	return ret;
180 }
181 
182 /*
183  * The actual xt_tables plugin.
184  */
185 static unsigned int idletimer_tg_target(struct sk_buff *skb,
186 					 const struct xt_action_param *par)
187 {
188 	const struct idletimer_tg_info *info = par->targinfo;
189 
190 	pr_debug("resetting timer %s, timeout period %u\n",
191 		 info->label, info->timeout);
192 
193 	mod_timer(&info->timer->timer,
194 		  msecs_to_jiffies(info->timeout * 1000) + jiffies);
195 
196 	return XT_CONTINUE;
197 }
198 
199 static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
200 {
201 	struct idletimer_tg_info *info = par->targinfo;
202 	int ret;
203 
204 	pr_debug("checkentry targinfo%s\n", info->label);
205 
206 	if (info->timeout == 0) {
207 		pr_debug("timeout value is zero\n");
208 		return -EINVAL;
209 	}
210 	if (info->timeout >= INT_MAX / 1000) {
211 		pr_debug("timeout value is too big\n");
212 		return -EINVAL;
213 	}
214 	if (info->label[0] == '\0' ||
215 	    strnlen(info->label,
216 		    MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) {
217 		pr_debug("label is empty or not nul-terminated\n");
218 		return -EINVAL;
219 	}
220 
221 	mutex_lock(&list_mutex);
222 
223 	info->timer = __idletimer_tg_find_by_label(info->label);
224 	if (info->timer) {
225 		info->timer->refcnt++;
226 		mod_timer(&info->timer->timer,
227 			  msecs_to_jiffies(info->timeout * 1000) + jiffies);
228 
229 		pr_debug("increased refcnt of timer %s to %u\n",
230 			 info->label, info->timer->refcnt);
231 	} else {
232 		ret = idletimer_tg_create(info);
233 		if (ret < 0) {
234 			pr_debug("failed to create timer\n");
235 			mutex_unlock(&list_mutex);
236 			return ret;
237 		}
238 	}
239 
240 	mutex_unlock(&list_mutex);
241 	return 0;
242 }
243 
244 static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)
245 {
246 	const struct idletimer_tg_info *info = par->targinfo;
247 
248 	pr_debug("destroy targinfo %s\n", info->label);
249 
250 	mutex_lock(&list_mutex);
251 
252 	if (--info->timer->refcnt == 0) {
253 		pr_debug("deleting timer %s\n", info->label);
254 
255 		list_del(&info->timer->entry);
256 		del_timer_sync(&info->timer->timer);
257 		cancel_work_sync(&info->timer->work);
258 		sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);
259 		kfree(info->timer->attr.attr.name);
260 		kfree(info->timer);
261 	} else {
262 		pr_debug("decreased refcnt of timer %s to %u\n",
263 			 info->label, info->timer->refcnt);
264 	}
265 
266 	mutex_unlock(&list_mutex);
267 }
268 
269 static struct xt_target idletimer_tg __read_mostly = {
270 	.name		= "IDLETIMER",
271 	.family		= NFPROTO_UNSPEC,
272 	.target		= idletimer_tg_target,
273 	.targetsize     = sizeof(struct idletimer_tg_info),
274 	.usersize	= offsetof(struct idletimer_tg_info, timer),
275 	.checkentry	= idletimer_tg_checkentry,
276 	.destroy        = idletimer_tg_destroy,
277 	.me		= THIS_MODULE,
278 };
279 
280 static struct class *idletimer_tg_class;
281 
282 static struct device *idletimer_tg_device;
283 
284 static int __init idletimer_tg_init(void)
285 {
286 	int err;
287 
288 	idletimer_tg_class = class_create(THIS_MODULE, "xt_idletimer");
289 	err = PTR_ERR(idletimer_tg_class);
290 	if (IS_ERR(idletimer_tg_class)) {
291 		pr_debug("couldn't register device class\n");
292 		goto out;
293 	}
294 
295 	idletimer_tg_device = device_create(idletimer_tg_class, NULL,
296 					    MKDEV(0, 0), NULL, "timers");
297 	err = PTR_ERR(idletimer_tg_device);
298 	if (IS_ERR(idletimer_tg_device)) {
299 		pr_debug("couldn't register system device\n");
300 		goto out_class;
301 	}
302 
303 	idletimer_tg_kobj = &idletimer_tg_device->kobj;
304 
305 	err =  xt_register_target(&idletimer_tg);
306 	if (err < 0) {
307 		pr_debug("couldn't register xt target\n");
308 		goto out_dev;
309 	}
310 
311 	return 0;
312 out_dev:
313 	device_destroy(idletimer_tg_class, MKDEV(0, 0));
314 out_class:
315 	class_destroy(idletimer_tg_class);
316 out:
317 	return err;
318 }
319 
320 static void __exit idletimer_tg_exit(void)
321 {
322 	xt_unregister_target(&idletimer_tg);
323 
324 	device_destroy(idletimer_tg_class, MKDEV(0, 0));
325 	class_destroy(idletimer_tg_class);
326 }
327 
328 module_init(idletimer_tg_init);
329 module_exit(idletimer_tg_exit);
330 
331 MODULE_AUTHOR("Timo Teras <ext-timo.teras@nokia.com>");
332 MODULE_AUTHOR("Luciano Coelho <luciano.coelho@nokia.com>");
333 MODULE_DESCRIPTION("Xtables: idle time monitor");
334 MODULE_LICENSE("GPL v2");
335 MODULE_ALIAS("ipt_IDLETIMER");
336 MODULE_ALIAS("ip6t_IDLETIMER");
337